Modern elevator apparatus used in buildings primarily comprise rails, counterweights, safety devices, a signal control system, elevator car, elevator doors and other components. Elevators are installed in shafts, usually adjacent to or connected to the machine room of a building.
Many modern elevators are operated by a traction drive, wherein at least one cable has one end connected to the elevator car, is held in position by a traction sheave, and has the other end of the cables connected to the counterweight. Usually, the elevator is then operated by a motor coupled to the traction sheave, which raises or lowers the elevator.
Elevators design requires high transmission efficiency between the motor, the traction shave, and the cable. The basic design goals for modern elevators require the elevator to be energy efficient, safe, and accurately find each level. Elevators are designed around a rated load, a maximum speed, outer dimensions, and the size of the elevator shaft.
Passenger elevators also need to be intelligently controlled, often by computers such that people can use the elevators without the assistance of a specialized operator. Conventional elevator design also requires users to choose their floors once they have stepped inside the elevator, which can be inefficient. Furthermore, the energy efficiency of elevators can be further increased.